Geographic Information Systems Asked by Anuruddha Marambe on September 8, 2020
I wrote a code for Land Surface Temperature (LST) from Landsat 8 images in google earth engine.
I have successfully calculated the following steps,
NDVI, fractional vegetation (fv), emissivity (EM), Brightness temperature (BT) is already a calculated band in Landsat image.
I wrote an equation for LST. It was successfully executed. However, I can not add the image to display. It gives an error called “LST: Layer error: Parameter ‘value’ is required.”
How to fix this error?
My code is,
//Take the landsat image
var bands=['B2', 'B3', 'B4', 'B5', 'B10']
var image= ee.Image(l8
.filterBounds(point)
.filterDate('2018-02-01', '2018-02-05')
.sort('CLOUD_COVER')
.first())
.select(bands).multiply(0.0001);
//Display the image
//Map.addLayer(image, {bands: ['B5', 'B4', 'B3'], max:0.9}, 'image');
//NDVI
var red=image.select('B4');
var nir=image.select('B5');
var ndvi= nir.subtract(red).divide(nir.add(red)).rename('NDVI');
print(ndvi);
var ndviparas={min:-1, max:1, palette:['blue', 'white', 'green']};
//Map.addLayer(ndvi, ndviparas, 'NDVI image');
// clip the NDVI image
var ndviClip = ndvi.clip(table);
Map.addLayer(ndviClip, {min: -1, max: 1, palette: ['FF0000', '00FF00']});
/*Export the image to an Earth Engine asset.
Export.image.toAsset({
image: ndviClip,
description: 'imageToAssetExample',
assetId: 'ndvi_kandy',
scale: 30
});
*/
//select thermal band 10(with brightness tempereature), no BT calculation
needed
var thermal10= image.select('B10').multiply(1000);
var thermal=thermal10.clip(table);
Map.addLayer(thermal, {min: 270, max: 400, palette: ['FF0000', '00FF00']});
// find the min of NDVI
var min = ee.Number(ndviClip.reduceRegion({
reducer: ee.Reducer.min(),
geometry: box,
scale: 30,
maxPixels: 1e9
}).values().get(0));
print(min)
var max = ee.Number(ndviClip.reduceRegion({
reducer: ee.Reducer.max(),
geometry: box,
scale: 30,
maxPixels: 1e9
}).values().get(0));
print(max)
//fractional vegetation
var fv = ndviClip.subtract(min).divide(max.subtract(min)).rename('FV');
print(fv)
Map.addLayer(fv, {min: 0, max: 1.5, palette: ['FF0000', '00FF00']},'FV');
//Emissivity
var a= Number('0.004');
var b= Number('0.986');
var EM=fv.multiply(a).add(b).rename('EMM');
Map.addLayer(EM, {min: 0, max: 1.5, palette: ['FF0000', '00FF00']},'EMM');
//LST c,d,f, p1, p2, p3 are assigned variables to write equaton easily
var c=Number('1');
var d=Number('0.00115');
var f=Number('1.4388');
var p1= thermal.multiply(d).divide(f);
var p2= Math.log(EM);
var p3= (p1.multiply(p2)).add(c);
var LST= (thermal.divide(p3)).rename('LST');
Map.addLayer(LST, {min: 0, max: 350, palette: ['FF0000',
'00FF00']},'LST');
/* R code
LST=(BT/(1+(0.00115*BT/1.4388)*log(EM)))
print(LST)
plot(LST)
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